MAY FLIES AND MIDGES OF NEW YORK 23 



c Between the lirst .-Hid second anal veins is a bunch of 3-4 long, 

 straight inliTealaries. conjoined hasally l>ol'ore their attachment 

 to llu principal veins: (he second anal vein nearly straight and 



unbranched Po 1 y m i t a r cy s 



CC Between the lirst and second anal veins are only shorter, simiati-, 



and slum-times forking interealaries, attached directly to the 



first anal ; the second anal vein sinuate and often branched 



(fig.3) 



(/ The median vein forked % to % its length; vein Cu 2 not more 



st rongly bent at base than the first anal Euthyplocia 



(/</ The fork of the median vein occupying not more than half its 

 length ; vein Cu 2 more strongly bent at base than is the first 

 anal (fig.3) 



The third anal vein simple, but attached to the hind margin by 



a number of crossveins ; in the narrow first fork of the 



median vein there are one or more crossveins before the 



origin of the vein M 2 ; male forceps four-jointed 



f Caudal setae 3, <$ and $ ; fore tarsus of female imago % as 



long as the tibia Ephemera 



if Caudal setae 2 in <$ and 3 in $; fore tarsus of 5 % as long 



as the tibia Pentagenia 



fff Caudal setae 2, rf and $ ; fore tarsus of $ as long as the 



tibia Hexagenia 



ce The third anal vein with a simple terminal fork and unattached 

 to the hind margin, although a few isolated short intereala- 

 ries lie between; in the wider first fork of the median vein 

 there is no crossveiu before the origin of vein M : ; male for- 

 ceps 3-jointed Potauianthus 



aa The cubital and first anal veins parallel at base (in a few forms with 



reduced and scanty venation, appearing a little divergent) 

 li Eyes of the male simple and remote; hind tarsi with 5 freely movable 

 segments ; venation never greatly reduced ; intercalary veins be- 

 tween the first and second anal veins unattached basally and in 

 two pairs, of which the pair nearer the hind angle is the longer 



i pi. 4, figs. 3 and 4) Heptageninae 



c Basal segment of the male fore tarsus not surpassed in length by any 



of the succeeding segments 

 d Second segment about as long as the first and longer than the 



third E p e o r n s 



dd Second segment shorter than the first and about equal to tin- 

 third Iron 



cc Basal segment of the male fore tarsus shorter than some of the 



eeeding segments 



d Basal segment of the male fore tarsus longer than the fifth seg 

 merit, the second and third segments of unequal length 



e The second segment longer than the third K d y n r u s 



ce The second segment shorter than the third < ' y n i g m a 



(1<1 The basal segment of the male fore 1ar<ns shorter than the fifth 

 segment, and the second and third segments of about equal 

 length 



